The minimum I would do is change oil/filter and coolant. If you can drain out old gas and put in new that would be nice. If you can't, definitely pour some kind of fuel injector cleaner or Lucas gas treatment in the tank. These products (and products like Sta-bil) can't restore old gas, they are meant to be used in fresh gas. Hopefully there wasn't too much ethanol in Wisconsin gas in 1998. Ethanol absorbs moisture (H2O) from the air and wreaks havoc on fuel systems. (I'm an avid motorcyclist. Soooo many motorcycles are parked in the fall and won't start in the spring because of fuel issues when people didn't put Sta-bil-or something similar- in the tank before storage. Anyway...) Also, you might experience various oil/transmission fluid leaks due to gaskets and seals drying up from lack of use over the years. Popular spots for leaks after long periods of storage are from the valve covers, oil pan, rear main seal, and (especially on an AOD) the rear seal (where the driveshaft goes into tranny). If you do a tune-up be aware the vacuum lines and plastic in the engine compartment is probably SUPER brittle! I tuned up my '92 as soon as I bought it after it had been parked for years, and I very quickly learned to be gentle when handling vacuum lines and such. They can just snap at the slightest touch when they get old. Good luck and keep us posted. Lots of good people here.